Passive optical network system and fault determination method

Abstract

In a passive optical network system, a parent station includes a reception circuit that receives an optical signal from each of child stations using a threshold used to identify if the optical signal is 0 or 1; a bandwidth setting unit that determines a time at which each child station sends an optical signal; a storage unit that stores thresholds and intensities of optical signals received from the child stations; and a control unit that sets a threshold, stored corresponding to a sending time, in,the reception circuit to control a reception of an optical signal. The control unit has a function that compares an intensity of a signal received from each child station at an optical signal reception time with information stored in the storage unit to detect and determine a fault in the child station or in the optical fiber connected to the child station.

Description

INCORPORATION BY REFERENCE[0001]The present application claims priority from Japanese application JP2008-234188 filed on Sep. 12, 2008, the content of which is hereby incorporated by reference into this application.BACKGROUND OF THE INVENTION[0002]The present invention relates to the configuration of a passive optical network system in which multiple optical network units share an optical transmission line and a method for determining a fault occurred in the system.[0003]Recently, FTTH(Fiber To The Home), which is an optical fiber service on access lines that serve subscribers, is introduced, and the communication services provided via this optical access network become more and more diversified as the transmission capacity grows.[0004]An optical communication network called a Passive Optical Network (hereinafter referred to as a PON) has been widely used as an optical access network. This is because the PON system allows multiple users to share an optical fiber, the optical line te...

AI Technical Summary

Benefits of technology

[0019]When a fault occurs in an ONU, the PON system and the operation method of the present invention determine the ONU and disconnect it from the PON system operation to minimize the effect on the communication wither other ONUs. In addition, the PON system and the operation method of the present invention reduce the maintenance time of a maintenance engineer in charge of maintaining the PON system, resulting in a reduction in the system operation cost and an increase in the maintenance efficiency.

[0020]When a continuous light is intentionally input to the PON system by a third party with an intention to disrupt the service, the PON system and the operation method of the present invention allow the user to determine the ONU and the light input position quickly and easily and disconnect that part from the OLT, thus increasing the security and reliability of the system operation.

Problems solved by technology

One of the cases where the management becomes difficult as described above is a case where a communication error occurs.

Failure to control an ONU in which an error has occurred sometimes results in a situation in which the ONU continuously emits light and, in the worst case, interferes the communication between other ONUs and the OLT.

At this time, because all ONUs use the common wavelength for the uplink signal, the currently available OLT in a station cannot determine which ONU is emitting light.

However, the procedure for visiting the sites for diagnosing all ONUs and branch optical fibers is time consuming and expensive.

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